BigDecimal 保留小数位/保留两位小数

BigDecimal decimal = new BigDecimal("1.98764432");
System.out.println(decimal);
BigDecimal setScale = decimal.setScale(4,BigDecimal.ROUND_HALF_DOWN);
System.out.println(setScale);
        
BigDecimal setScale1 = decimal.setScale(4,BigDecimal.ROUND_HALF_UP);
System.out.println(setScale1);

运行结果

1.98764432

1.9876

1.9877

参数定义

ROUND_CEILING Rounding mode to round towards positive infinity. 向正无穷方向舍入 ROUND_DOWN Rounding mode to round towards zero. 向零方向舍入 ROUND_FLOOR Rounding mode to round towards negative infinity. 向负无穷方向舍入 ROUND_HALF_DOWN Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round down. 向（距离）最近的一边舍入，除非两边（的距离）是相等,如果是这样，向下舍入, 例如1.55 保留一位小数结果为1.5 ROUND_HALF_EVEN Rounding mode to round towards the "nearest neighbor" unless both neighbors are equidistant, in which case, round towards the even neighbor. 向（距离）最近的一边舍入，除非两边（的距离）是相等,如果是这样，如果保留位数是奇数，使用ROUND_HALF_UP ，如果是偶数，使用ROUND_HALF_DOWN ROUND_HALF_UP Rounding mode to round towards "nearest neighbor" unless both neighbors are equidistant, in which case round up. 向（距离）最近的一边舍入，除非两边（的距离）是相等,如果是这样，向上舍入, 1.55保留一位小数结果为1.6 ROUND_UNNECESSARY Rounding mode to assert that the requested operation has an exact result, hence no rounding is necessary. 计算结果是精确的，不需要舍入模式 ROUND_UP Rounding mode to round away from zero. 向远离0的方向舍入